Lumpy earth is used to visualize its gravitational field. 
Discussion
That is the actual shape of the planet. Not only to visualise gravitational field. Its called oblate spheroid or geoid lumpy earth is not a shape.
Lumpy earth is used to visualize its gravitational field.
That is the actual shape of the planet. Not only to visualise gravitational field. Its called oblate spheroid or geoid lumpy earth is not a shape.
